Method of making roofing battens

ABSTRACT

A seamless tube useful in making a roofing batten is extruded from a polymeric material consisting essentially of a major amount of poly(ethylene terephthalate) and a minor amount of at least one polyolefin, flattened in a vacuum sizer so as to define two plies, and milled and drawn so as to orient the tube longitudinally. As milled and drawn, the tube is oriented so as to have a tensile strength of at least about 25,000 psi in a longitudinal direction. The plies are punched so as to have holes therethrough at spaced intervals along the tube. When used to make a roofing batten to coact with conventional fasteners, such as roofing screws, the tube exhibits superior characteristics of split resistance and pull-through resistance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 719,981, filedJun. 24, 1991, now abandoned, which is a CIP of Ser. No. 631,219, filedDec. 21, 1990, now U.S. Pat. No. 5,161,342, which is a continuation ofSer. No. 294,324, filed Jan. 6, 1989, now abandoned.

TECHNICAL FIELD OF THE INVENTION

This invention pertains to a seamless tube, which is useful in making aroofing batten, and to a related method of manufacture. As extruded froma polymeric material, the tube is flattened so as to define two pliesand a substantially collapsed lumen and is oriented longitudinally,preferably so as to have a tensile strength of at least about 25,000 psiin a longitudinal direction.

BACKGROUND OF THE INVENTION

Roofing battens are used widely in securing flexible membranes tounderlying materials. Mechanical fasteners, such as roofing screws, arepassed through the battens, which may be pre-punched with holes toaccommodate such fasteners. Typically, roofing battens comprise metal,wooden, or polymeric strips.

A polymeric material having particular utility in making a roofingbatten is disclosed in Kish et al. U.S. Pat. No. 4,963,430. As disclosedtherein, the polymeric material comprises a major amount ofpoly(ethylene terephthalate) and a minor amount of at least onepolyolefin, such as polypropylene. As disclosed therein, such materialcan be substantially mono-axially oriented so as to have a tensilestrength of at least about 25,000 psi in the oriented direction.

Other roofing battens made from polymeric materials are disclosed inRussell et al. U.S. Pat. No. 4,718,211 and in Schauffele U.S. Pat. No.4,445,306. One possible arrangement of roofing battens on a roof isdisclosed in Kelly U.S. Pat. No. 4,736,562.

It is disclosed in the copending patent application (Hasan et al. U.S.Ser. No. 07/294,324 filed Jan. 6, 1989, now abandoned) noted above that,as compared to a roofing batten having a single ply, a roofing battenhaving two plies with a combined thickness equal to the thickness of thesingle ply provides increased pull-through resistance when used withmechanical fasteners.

Heretofore, for purposes disclosed in the copending application notedabove, it has been preferred to make a roofing batten with two plies, inone piece, from a wide strip by folding such strip longitudinally andusing an adhesive to bond half portions of such strip to each other. Itwould be highly desirable to eliminate such strip-folding andadhesive-bonding steps.

A need has been created, to which this invention is addressed, for abetter method of manufacturing a roofing batten with two plies.

SUMMARY OF THE INVENTION

In addressing the aforenoted need, this invention provides a novelarticle, namely a seamless tube useful in making a roofing batten. Theseamless tube is extruded from a polymeric material, flattened so as todefine two plies and a substantially collapsed lumen, and orientedlongitudinally. The polymeric material may be any polymeric materialthat is capable of being extruded and that is capable of being orientedthrough drawing with or without compression.

Preferably, the polymeric material is similar to the polymeric materialdisclosed in Kish et al. U.S. Pat. No. 4,963,430 and contains a majoramount of poly(ethylene terephthalate) and a minor amount of at leastone polyolefin. Preferably, moreover, the tube is oriented so as to havea tensile strength of at least about 25,000 psi in a longitudinaldirection.

Other polymeric materials that may be alternatively used includepoly(ethylene terephthalate) and polyolefins, such as polypropylene.Polyamides (nylons) may be alternatively used. For making a roofingbatten, the polymeric material disclosed in the Kish et al. patent notedabove is preferred because of its superior characteristics of splitresistance and pull-through resistance when used with mechanicalfasteners, such as roofing screws.

So as to enhance the utility of the tube for making a roofing batten,the plies may have holes therethrough at spaced intervals along the tubeso as to accommodate mechanical fasteners, such as roofing screws.

According to this invention, moreover, a seamless tube useful in makinga roofing batten is manufactured by a novel method comprising steps ofextruding a seamless tube from a polymeric material, flattening the tubeso as to define two plies and a substantially collapsed lumen, andorienting the tube longitudinally. If the preferred material noted aboveis used, the tube may be then oriented so as to have a tensile strengthof at least about 25,000 psi in a longitudinal direction. Furthermore,after the tube has been oriented, the plies may be desirably providedwith holes therethrough at spaced intervals along the tube.

In a preferred mode for carrying out the novel method, the tube isextruded with a substantially opened lumen, whereupon the tube isflattened substantially by being sized in a vacuum sizer, which isarranged to flatten the tube and to provide the tube with asubstantially elongate lumen. Thereupon, in the preferred mode, the tubeis oriented by milling and drawing the tube. Finally, in the preferredmode, holes are provided through the tube at spaced intervals along thetube after the tube has been oriented.

Although a seamless tube according to this invention has particularutility when used to make roofing battens, it is contemplated that sucha tube may have other similar and dissimilar uses.

These and other objects, features, and advantages of this invention areevident from the following description of a preferred embodiment of thisinvention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, perspective, partly exploded, verticalcross-sectional view of a roofing construction comprising a roofingdeck, a slab of fibrous roofing insulation, two overlapped membranes,and plural roofing battens made from a seamless tube according to thisinvention, along with roofing screws coacting with such roofing battens.

FIG. 2 is a fragmentary, perspective view of one end portion of aseamless tube according to this invention.

FIG. 3 is a cross-sectional view of the same tube, as extruded.

FIG. 4 is a cross-sectional view of the same tube, as flattened.

FIG. 5 is a cross-sectional view of the same tube, as milled and drawn.

FIG. 6 is a diagrammatic representation of a processing line useful inmanufacturing a seamless tube according to this invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

As shown in FIG. 1, a roofing structure 10 incorporating this inventioncomprises a roofing deck 12 made of corrugated metal, a slab 14 offibrous roofing insulation overlying the deck 12, one or possibly tworoofing membranes made of a flexible, waterproof material, namely alower membrane 16 covering the slab 14 and an upper membrane 18 coveringthe lower membrane 16, and plural roofing battens 20 overlying the uppermembrane 18 at spaced intervals. Roofing screws 22 having threadedshanks 24 and enlarged heads 26 coact with the battens 20 to secure themembranes 16, 18, and the slab 14 to the deck 12. Thus, the battens 20stabilize the membranes 16, 18, against ballooning excessively underwind loads. According to this invention, each batten 20 is made from aseamless tube 30, which is extruded from a polymeric material. The tube30 is flattened, so as to have a substantially elongate lumen 32 and soas to define two plies 34, 36, and is oriented longitudinally. The plies34, 36, are punched so as to have a series of holes 38 through the plies34, 36, at spaced intervals along such tube 30. The holes 38 aredimensioned to permit the screw shanks 24 to pass through the holes 30but not to permit the screw heads 26 to pass therethrough. The plies 34,36, exhibit excellent pull-through resistance when used with mechanicalfasteners, such as the screws 22.

Preferably, the tube 30 is extruded from the polymeric materialdisclosed in Kish et al. U.S. Pat. No. 4,963,430, the disclosure ofwhich is incorporated herein by reference. Such material, when extrudedand oriented, exhibits superior characteristics of split resistance andpull-through resistance when used with mechanical fasteners, such as thescrews 22. As disclosed therein, the polymeric material contains a majoramount (e.g., from about 80% to about 97% by weight) of poly(ethyleneterephthalate) and a minor amount (e.g., from about 3% to about 20% byweight) of at least one polyolefin, preferably polypropylene. Asdisclosed therein, the polyolefin may be a blend of polypropylene,maleic anhydride grafted polypropylene, and ethylene-propylene rubber. Apreferred composition for the polymeric material is, by weight,approximately 92% poly(ethylene terephthalate), 6% polypropylene, 0.8%maleic anhydride grafted polypropylene, and 1.2% ethylene-propylenerubber.

Preferably, the tube 30 is oriented longitudinally so as to have atensile strength of at least about 25,000 psi in a longitudinaldirection. It is disclosed in the Kish et al. patent noted above that astrip extruded from the polymeric material disclosed therein can bemono-axially oriented so as to have such a tensile strength. The tube 30is extruded in an indeterminate length. Preferably, after the tube 30has been flattened but before it is oriented, the tube 30 has a width ofapproximately 1.7 inches and a combined thickness of approximately 150to 180 mils for the plies 34, 36, as shown in FIG. 4. Preferably, afterthe tube 30 has been oriented, the tube 30 has a width of approximatelyone inch and a combined thickness of approximately 50 mils for the plies34, 36, as shown in FIG. 5.

As shown in FIG. 6, the roofing batten 10 can be efficientlymanufactured in a processing line comprising known apparatus. Theprocessing line is described below.

The respective constituents of a suitable composition, such as thepreferred composition noted above, are fed into an extruder 100. In theextruder 100, such composition is blended, heated to a suitabletemperature (e.g., a temperature in a range from approximately 520° F.to approximately 550° F.) so that such composition becomes plastic, andextruded through a suitable die 110 including a mandrel (not shown) soas to form a seamless tube 30. Preferably, the tube 30 is extruded so asto have a substantially circular mandrel 32, as shown in FIG. 3. Thetube 30 may be alternatively extruded so as to have a differently shapedmandrel (not shown) such as a substantially rectangular mandrel.

While the tube 30 remains plastic, the tube 30 is fed through a vacuumsizer 120, in which the tube 30 is flattened so as to define two plies34, 36, and in which the tube 30 is sized so as to have a substantiallyelongate lumen 32, as shown in FIG. 4. The tube 30 solidifies in thevacuum sizer 120, which prevents the plies 34, 36, from welding to eachother before the tube 30 solidifies. Moreover, as discussed below, theplies 34, 36, do not weld to each other after the tube 30 solidifies.The tube 30 is pulled from the vacuum sizer 120 by a pair of endlessbelts 130.

Via the endless belts 130, the tube 30 is fed through a pair of millingrolls 140, which compress the tube 30 and causes the lumen 32 to besubstantially collapsed. From the milling rolls 140, the tube is drawnover a set of first rollers 150 defining a first bridle. The firstrollers 150 are rotated at surface speeds relative to the surface speedsof the milling rolls 140 so as to provide a draw ratio in a range fromapproximately 1.0 to approximately 1.2. Because of elastic recovery ofthe polymeric material leaving the milling rolls 140, a draw ratio ofapproximately 1.0 corresponds to an elongation of approximately 25%.Thus, as compressed by the milling rolls 140 and drawn by the firstrollers 150, the tube 30 is oriented longitudinally.

From the first rollers 150, the tube 30 is fed through an annealing unit170, in which the tube 30 is annealed at a suitable temperature (e.g.,approximately 250° F.) so as to set the elongation of the tube 30. Thetube 30 is then drawn over a set of second rollers 160 defining a secondbridle. The second rollers 160 are rotated at surface speeds relative tothe surface speeds of the first rollers 150 so as to define a draw ratioof approximately 0.95.

The annealed tube 30 is then driven through a water bath 172, whichcools the tube 30.

From the water bath 172, the tube 30 is fed through a punching unit 180,in which the holes 38 are punched through the plies 34, 36. From thepunching unit 180, the tube 30 is fed into a winding unit 190, in whichthe flattened, oriented, punched tube 30 is wound onto spools. The tube30 may be then cut into suitable lengths, each to constitute a roofingbatten, as exemplified by the roofing battens 20.

As mentioned above, the plies 34, 36, do not weld to each other when thetube 30 is flattened. Unexpectedly, the plies 34, 36, do not weld toeach other when the tube 30 is milled, drawn, and annealed.

An alternative method for making a seamless tube according to thisinvention is contemplated, in which such milling rolls are not used, andin which the flattened tube is oriented by being drawn over a short gapbetween two sets of rollers being rotated at different speeds.

Having superior characteristics of split resistance and pull-throughresistance, a roofing batten made from a seamless tube according to thisinvention performs as well as the two-ply batten disclosed in thecopending application (Hasan et al. U.S. Ser. No. 07/294,324 filed Jan.6, 1989) noted above.

As a possible modification of the preferred embodiment described above,the plies of the seamless tube may be adhesively bonded to each other,via an adhesive introduced before the tube is milled.

Various other modifications may be also made in the preferred embodimentdescribed above, and in the processing line described above, withoutdeparting from the scope and spirit of this invention.

We claim:
 1. A method of manufacturing a roofing batten, for securingroofing materials to a roofing substructure as a result of said roofingbatten being disposed atop said roofing materials and being secured tosaid roofing substructure by means of a plurality of fasteners arrangedin longitudinally extending, laterally spaced rows and passing throughsaid roofing batten, said roofing materials and said roofingsubstructure, comprising the steps of:extruding a polymeric material soas to form a seamless tube having a longitudinal axial extent;flattening said seamless tube along said longitudinal axial extent so asto define two superimposed roofing batten plies integrally connectedtogether along oppositely disposed, laterally spaced, longitudinallyextending side edge portions thereof and with a substantially collapsedlumen defined therebetween; orienting said seamless tube longitudinally;punching holes through both of said two roofing batten plies of saidflattened seamless tube at spaced intervals along said longitudinalaxial extent of said flattened seamless tube, wherein each hole withinone of said two superimposed roofing batten plies is coaxially alignedwith a hole within the other one of said two superimposed roofing battenplies, for receiving said plurality of fasteners for securing saidroofing batten atop said roofing materials and to said roofingsubstructure; and cutting said flattened seamless tube, having saidholes provided therein, to predetermined lengths so as to define aplurality of roofing battens having said predetermined lengths such thateach one of said roofing battens extends at least between two axiallyspaced positions at which at least two of said plurality of fasteners,arranged within said longitudinally extending, laterally spaced, rows,are to be disposed.
 2. The method of claim 1 wherein the polymericmaterial is oriented so as to have a tensile strength of at least about25,000 psi in a longitudinal direction.
 3. The method of claim 1 whereinthe polymeric material comprises a major amount of poly(ethyleneterephthalate) and a minor amount of at least one polyolefin, andwherein the tube is oriented so as to have a tensile strength of atleast about 25,000 psi in a longitudinal direction.
 4. The method ofclaim 3 wherein the tube is extruded with a substantially circularlumen, and wherein the method comprises a step of flattening the tubesubstantially in a vacuum sizer, which is arranged to flatten the tubeand to provide the tube with a substantially elongate lumen.
 5. Themethod of claim 4 wherein the tube is oriented by milling and drawingthe tube.
 6. A method as set forth in claim 3, wherein:said major amountof poly(ethylene terephthalate) comprises approximately 80-97% byweight; and said minor amount of said polyolefin comprises approximately3-20% by weight.
 7. A method as set forth in claim 6, wherein:saidpolyolefin comprises polypropylene.
 8. A method as set forth in claim 6,wherein:said polyolefin comprises a blend of polypropylene, maleicanhydride grafted polypropylene, and ethylene-propylene rubber.
 9. Amethod as set forth in claim 8, wherein:said polymeric materialcomprises approximately 92% by weight poly(ethylene terephthalate), 6%by weight polypropylene, 0.8% by weight maleic anhydride graftedpolypropylene, and 1.2% by weight ethylene-propylene rubber.
 10. Amethod as set forth in claim 5, wherein:said flattened seamless tube hasa combined thickness of approximately 150-180 mils prior to beingoriented and a combined thickness of approximately 50 mils after beingoriented by said milling, and a width of approximately 1.7 inches priorto being oriented and a width of approximately 1.0 inch after beingoriented by said drawing.
 11. A method as set forth in claim 5,wherein:said drawing is performed in accordance with a draw ratio withinthe range of approximately 1.0-1.2.
 12. A method as set forth in claim11, wherein:said flattened seamless tube is elongated by approximately25% as a result of experiencing a draw ratio of approximately 1.0; andsaid drawn seamless tube is then annealed at a predetermined temperatureso as to set said elongation of said flattened seamless tube.
 13. Amethod as set forth in claim 12, wherein:said predetermined temperatureis approximately 250° F.
 14. A method as set forth in claim 12,wherein:said annealed seamless tube is subsequently cooled within awater bath.
 15. A method of manufacturing a roofing batten, for securingat least one flexible, water-impervious sheet membrane to a roofingsubstructure in order to seal said roofing substructure against liquidpenetration as a result of said roofing batten being disposed atop saidat least one flexible, water-impervious sheet membrane and being securedto said roofing substructure by means of a plurality of fastenersarranged in longitudinally extending, laterally spaced rows and passingthrough said roofing batten, said at least one flexible,water-impervious sheet membrane, and said roofing substructure,comprising the steps of:extruding a polymeric material so as to form aseamless tube having a longitudinal axial extent; flattening saidseamless tube along said longitudinal axial extent so as to define twosuperimposed roofing batten plies integrally connected together alongoppositely disposed, laterally spaced, longitudinally extending sideedge portions thereof and with a substantially collapsed lumen definedtherebetween; orienting said seamless tube longitudinally; punchingholes through both of said two roofing batten plies of said flattenedseamless tube at spaced intervals along said longitudinal axial extentof said flattened seamless tube, wherein each hole within one of saidtwo superimposed roofing batten plies is coaxially aligned with a holewithin the other one of said two superimposed roofing batten plies, forreceiving said plurality of fasteners for securing said roofing battenatop said at least one flexible, water-impervious sheet membrane and tosaid roofing substructure; and cutting said flattened seamless tube,having said holes provided therein, to predetermined lengths so as todefine a plurality of roofing battens having said predetermined lengthssuch that each one of said roofing battens extends at least between twoaxially spaced positions at which at least two of said plurality offasteners, arranged within said longitudinally extending, laterallyspaced, rows, are to be disposed.
 16. The method as set forth in claim15, wherein:said polymeric material is oriented so as to have a tensilestrength of at least approximately 25,000 psi in a longitudinaldirection.
 17. The method as set forth in claim 15, wherein:saidpolymeric material comprises a major amount of poly(ethyleneterephthalate) and a minor amount of at least one polyolefin.
 18. Themethod as set forth in claim 17, wherein:said major amount of saidpoly(ethylene terephthalate) comprises approximately 80-97% by weight;and said minor amount of said polyolefin comprises approximately 20-3%by weight.
 19. The method as set forth in claim 18, wherein:saidpolyolefin comprises polypropylene.
 20. The method as set forth in claim18, wherein:said polyolefin comprises a blend of polypropylene, maleicanhydride grafted polypropylene, and ethylene-propylene rubber.
 21. Themethod as set forth in claim 20, wherein:said polymeric materialcomprises approximately 92% by weight poly(ethylene terephthalate), 6%by weight polypropylene, 0.8% by weight maleic anhydride graftedpolypropylene, and 1.2% by weight ethylene-propylene rubber.